Fluid chemicals are injected into trees to obtain a variety of advantages, such as feeding the tree, treating it with fungicides or insecticides, and for inhibiting its growth. Numerous devices have been available for the injection of such fluid substances into trees. In one such system, shown in U.S. Pat. No. 4,505,067, injection of fluid is provided using injectors connected with cylinders and a reservoir of liquid to be injected. Pistons within the cylinders are connected to an operating arm used to manually drive the pistons and inject the fluid.
Other systems provide injection of the fluid chemicals under pressure. U.S. Pat. No. 3,992,813, for example, discloses a treating system wherein fluid is introduced into a tree using a plurality of injectors connected via hose assemblies to a source of fluid to be injected and a portable source of pressure to force the liquid into the tree. One of the problems with such treatment systems has been controlling and monitoring the amount of fluid that is injected. Thus, for example, while the injection of a pre-measured tank of fluid chemicals seems to provide an adequate indication of the amount of fluid injected, air contained in the system often disguises the true measure of the substance injected.
In the past, systems with multiple injectors have also been unable to operate independently. Such systems required all of the injectors to be empty before any could be refilled. Since different portions of a tree often accept fluid at different rates, the operator of such systems could not refill each injector as it was emptied. Instead, the operator was forced to wait for all injectors to empty, at which time the unit could be refilled and injection operations continued.
A further problem with prior pressurized tree injection systems, has been the difficulty in transporting such systems to the site of the tree to be injected. Another problem has been the inability of such systems to inject variable amounts of fluids, depending on the tree size or the type of chemical required to be injected. Such systems have also failed to inject the desired amount of fluid on a continuing basis. If, for example, an operator desired to repeatedly inject a non-standard volume of fluid which required adjustment of the injector, re-adjustment to the desired volume setting was required prior to each of the repeated injections.